The present invention relates in general to semiconductor devices for electric power conversion using semiconductor switching elements and, in more particular, to a technique for suppressing occurrence of rapid potential variation or xe2x80x9cjump-upxe2x80x9d of voltages during switching operations while reducing the device in size or dimension.
In recent years, electric power conversion devices employing high-speed semiconductor switching elements typically including insulated-gate bipolar transistors (IGBTS) have been used in a wide variety of technical fields. As the capacity increases, the power converter devices are in many cases configured from a converter and more than one smoothing capacitor plus an inverter rather than a mere rectifier circuit in order to let electrical power xe2x80x9creincarnatexe2x80x9d to the power supply.
As one example of such approach, the circuit configuration of a three-phase power converter apparatus such as a variable frequency power supply is shown in FIG. 3. In brief, a converter 3 and an inverter 4 are connected together via a group of smoothing capacitors 1. The converter 3 is generally constituted from IGBT modules 311-323 and conductors 331-363 for connection therebetween.
In addition, the IGBT modules 311-323 are each formed of a switching element (here, IGBT) and a diode operatively associated therewith. The positive polarity-side conductors 331-333 are connected through a common conductor 21a to a conductor 21 for connecting capacitorsxe2x80x94 positive polarities together via a common conductor 37. Similarly the negative polarity-side conductors 341-343 are connected through a common conductor 22a to a conductor 22 for connecting the capacitors"" negative polarities together via a common conductor 38. As in the converter 3, the inverter 4 is similarly constituted from IGBT modules 411-423 and conductors 431-463, wherein positive polarity-side conductors 431-433 are connected through a common conductor 21b to a conductor 21 for connecting the capacitors"" positive polarities together via a common conductor 47. Similarly negative polarity-side conductors 441-443 are connected via a common conductor 22b to a conductor 22 for connecting the capacitors"" negative polarities together by a common conductor 48. Although not specifically shown in the drawing, an alternate current (AC) power supply part is connected to the converter 3 via AC conductors 361-363 whereas a load, such as a motor, is coupled to the inverter 4 via AC conductors 461-463.
In the power converter device thus arranged, a voltage can potentially jump up in turn-off events due to an energy being accumulated upon power-up or electrization to the lead wire inductance of circuitry. If this xe2x80x9cjump-upxe2x80x9d voltage potentially goes beyond the inherent withstanding or breakdown voltage level of switching elements, then the elements might lead to destruction; thus, an attempt is made to suppress such voltage jump-up by connecting a snubber circuit, although not shown in FIG. 3. Unfortunately the use of such snubber circuit serves as a bar to achievement of the device downsizing; thus, it is important to suppress or minimize the lead wire inductance of the circuit. In order to suppress such circuit lead wire inductance, a variety of approaches have been employed until today including, but not limited to, a technique for using a multilayer conductor structure with reverse-direction currents opposing each other.
One example is disclosed in Japanese Application Patent Laid-Open Publication No. Hei 08-19245, wherein the lead wire inductance is reduced by arranging a group of semiconductor switching elements and a capacitor group so that all of them are arranged by a multilayered conductor.
However, in cases where the power converter device further increases in size resulting in a likewise increase in parallel array number of capacitors and/or an increase in dimensions of switching elements, the multilayer conductor per se is made larger in size, which leads to difficulties in the manufacture of such multilayer conductor while at the same time increasing workloads for connection to respective terminals during conductor connection processes, resulting in unwanted increases in production costs.
The prior art electric power conversion device made up from a plurality of semiconductor switching elements and a plurality of capacitors in the way stated above is encountered with a problem that unwanted increases in costs in conductor manufacturing parts assembly processes occur due to inductance reduction for suppression of a rapidly potentially varying or xe2x80x9cjump-upxe2x80x9d voltage in accordance with an increase in capacity of the power conversion device.
It is therefore a primary object of the present invention to provide a semiconductor electric power conversion device preferably adapted to achieve inductance reduction by use of conductors of simplified structure to thereby suppress any possible jump-up voltages.
To attain the foregoing object the instant invention provides an improved semiconductor electric power conversion device including a converter unit and an inverter unit each having a group of parallel-connected capacitors and a plurality of positive polarity side switching elements being connected to a positive polarity terminal of the capacitor group plus a plurality of negative polarity side switching elements as connected to a negative polarity terminal of the capacitor group, wherein the device comprises a first connection section for connecting together a first conductor being connected to the positive terminal of the capacitor group and a second conductor as connected to the positive polarity of the positive polarity side switching elements making up the inverter and a second connection section for connecting thereto a third conductor as connected to the positive polarity of the positive polarity side switching elements making up the inverter, and a third connection section for connecting together a fourth conductor being connected to the negative terminal of the capacitor group and a fifth conductor as connected to the negative polarity of the negative polarity side switching elements making up the converter and a fourth connection section for connecting thereto a sixth conductor as connected to the negative polarity of the negative polarity side switching elements constituting the inverter, and wherein the first conductor and the fourth conductor are formed to have a multilayer structure while letting the second conductor and fifth conductor be formed into a multilayer structure with the third conductor and sixth conductor being formed into a multilayer structure.
It should be noted here that respective capacitors making up the capacitor group are on the same plane while disposing the first connection section and the third connection section on the same side with respect to an infinite plane containing therein a line segment coupling together at least two terminals of the terminals of the capacitor group and being at right angles to the aforesaid plane and also disposing the second connection section and the fourth connection section be disposed at the opposite side thereto, wherein the first to fourth connection sections have a plurality of subdivided connection conductors with the first connection section and the third connection section being disposed in close proximity to each other in the state that these are electrically isolated from each other and also with the second connection section and fourth connection section being disposed adjacent to each other in the state that these are electrically isolated from each other.
In addition, respective capacitors making up the capacitor group are all the same in shape and are disposed in the same direction.
Additionally, the subdivided connection conductors of the first to fourth connection sections are all the same in width.
Additionally the connection conductors of the first connection section and the second connection section are subdivided into the same number of portions whereas the connection sections of the third connection section and the fourth connection section are divided into the same number of portions.
Additionally a total number of the subdivided connection conductors of the first connection section and the third connection section is greater than the number of the parallel-connected capacitors in the capacitor group.
Additionally a plurality of single-phase units are connected for constitution of a multiple-phase electric power conversion unit.